This invention relates to the baling of fiber and methods of forming such bales to facilitate shipment. The invention further relates to a method of forming bales having specific densities and dimensions so that a plurality of the bales will substantially fully occupy the interior volume of a transport and will substantially fully equal the maximum payload of the transport.
Cellulose fiber is an exceptionally useful material in the textile and other industries. It is widely used in highly absorbent products such as diapers. Fibrous material made by the procedure and apparatus described in co-pending application filed Oct. 31, 1990 entitled "Fiber Treatment Apparatus" to Allen R. Carney et al, application Ser. No. 07/607,268 (pending) (incorporated herein by reference) are particularly valuable.
It is frequently necessary to transport the fiber material from the side where it is manufactured to the location where it is to be used. This presents a problem because the fiber is very bulky, particularly if manufactured by a preferred method wherein fiber is maintained in substantially individual form during drying and crosslinking steps. Shipping such a material would be prohibitively expensive unless it could first be reduced in volume.
One method for transporting bulk cellulose fiber would be to form densified sheets which could be more easily handled and tightly packed in a trailer, shipping container, or rail car. According to U.S. Pat. No. 4,822,453, is difficult to form densified sheets of dry crosslinked fibers. When sheets of such material are refluffed, it is found that the fibers have been damaged and that nowhere near the full bulk of the original fibers can be restored. One consequence of compressing the fibers with pressures sufficient to form densified sheets is the fiber's subsequent inability to regain its prior absorbency. The resiliency of crosslinked fiber makes it particularly difficult to form sheets of that material without damaging the fiber.
Another option would be to crush the fiber material into freestanding bales. Vertical presses are capable of compressing high-bulk fiber having an initial density of about 0.008 g/cc to a final freestanding or unrestrained density of 0.41 g/cc or more. Final freestanding bale densities of about 0.41 g/cc would be required to maintain the high-bulk, crosslinked cellulose fiber in the shape of a bale, following retraction of a bale press, without the use of bale restraints. But, such bales would have the same shortcomings as sheets. A great deal of force must be applied to produce freestanding bales of meaningfully increased density. The fiber is damaged during compression and cannot thereafter be restored to anywhere near full volume or absorbency. For example, tests indicate that compressing such fiber to a freestanding bale which maintains a density of about 0.41 g/cc results in a 43% loss in bulk.
Certain bulk materials, such as hay, are formed into restrained bales for transport. Balers are currently available to form restrained bales of paper products or paper waste products such as old corrugated containers (o.c.c.). For example, Maren Engineering Corporation manufactures an automatic baler capable of continuously forming bales of o.c.c. and other paper products. The operating pressure of the Maren baler, model number 203, is approximately 155 kgs/square centimeter. The application of this pressure can produce compressed densities of about o.c.c. to 0.48 g/cc for certain materials. Other examples of prior art balers used for baling o.c.c. and paper waste products are available from C & M Baler Company of Winston-Salem, N.C. No one has heretofore thought to use such balers for baling high-bulk resilient fibers.